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Multilingual Illustrated DVD [Tutorial]

The Biology of Prenatal Development

Introducing the Multilingual Illustrated DVD
Explore the fascinating imagery and facts presented in The Biology of Prenatal Development at your own pace. Each clip from the program is accompanied by its corresponding written script. Select Play Movie to watch any clip. Select See Snapshots to view high resolution images. See the program script and subtitles in 88 languages by using the Choose Language drop-down menu and clicking Refresh. Subtitles are displayed in your chosen language and may be turned on and off by clicking the button found in the lower right corner of the movie player. A "full screen" option is also available by clicking the button.

National Geographic Society This program is distributed in the U.S. and Canada by National Geographic and EHD. [learn more]

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Embryonic Development: 4 to 6 Weeks

Chapter 11   4 Weeks: Amniotic Fluid

By 4 weeks the clear amnion surrounds the embryo in a fluid-filled sac. This sterile liquid, called amniotic fluid, provides the embryo with protection from injury.

Chapter 12   The Heart in Action

The heart typically beats about 113 times per minute.

Note how the heart changes color as blood enters and leaves its chambers with each beat.

The heart will beat approximately 54 million times before birth and over 3.2 billion times over the course of an 80-year lifespan.

Chapter 13   Brain Growth

Rapid brain growth is evidenced by the changing appearance of the forebrain, midbrain, and hindbrain.

Chapter 14   Limb Buds

Upper and lower limb development begins with the appearance of the limb buds by 4 weeks.

The skin is transparent at this point because it is only one cell thick.

As the skin thickens, it will lose this transparency, which means that we will only be able to watch internal organs develop for about another month.

Chapter 15   5 Weeks: Cerebral Hemispheres

Between 4 and 5 weeks, the brain continues its rapid growth and divides into 5 distinct sections.

The head comprises about 1/3 of the embryo's total size.

The cerebral hemispheres appear, gradually becoming the largest parts of the brain.

Functions eventually controlled by the cerebral hemispheres include thought, learning, memory, speech, vision, hearing, voluntary movement, and problem-solving.

Chapter 16   Major Airways

In the respiratory system, the right and left main stem bronchi are present and will eventually connect the trachea, or windpipe, with the lungs.

Chapter 17   Liver and Kidneys

Note the massive liver filling the abdomen adjacent to the beating heart.

The permanent kidneys appear by 5 weeks.

Chapter 18   Yolk Sac and Germ Cells

The yolk sac contains early reproductive cells called germ cells. By 5 weeks these germ cells migrate to the reproductive organs adjacent to the kidneys.

Chapter 19   Hand Plates and Cartilage

Also by 5 weeks, the embryo develops hand plates, and cartilage formation begins by 5 1/2 weeks.

Here we see the left hand plate and wrist at 5 weeks and 6 days.

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